Method of producing screw-threads by grinding.



G. A. HATTERSLEY & L. KOENIG.

METHOD OF PRODUCING SCREW THREADS BY GRINDING.

APPLICATION FILED AUG. 14 1910' 985,412, Patented Feb.28,1911.

3 SHEETSSHEET l.

G. A. HATTER-SLEY I; L. KOENIG.

G SCREW THREADS BY GRINDING.

APPLICATION FILED AUG. 1. 1910.

METHOD OF PRODUGIN Patented Feb. 28

3 SHEETS-SHEET 3.

fizvsnfars.

APPLICATION FILED AUG. 1, 1910.

IAWIA G. A. HATTERSLEY & L. KOENIG.

METHOD OF PRODUCING QGREW THREADS BY GRINDING.

cnonon A. nnrrrnnsnns, or nonwoon, AND reins sssronons 'ro THE yroron sens & LOCK co, or

TION OF OHIO.

METHOD OF PRODUCING SCREW-THREADS BY GRINDING.

Specification of Letters Patent.

Fntentcd Feb. 28, 1911.

Application filed August 1, 1910. Serial Ito. 574,976.

T all whom it may concern:

Be t known that we, Gnouor A. HAr'rnRs- Lnr and LOUIS Konn1u,c:itizens of the United States, the first residing at Norwood, the other in Cincinnati, both in' Hamilton county, State ofOh-io, have invented a certain new and useful Method for Producing Screw-Threads by Grinding; and we do declare the 'following to he a clear, full. and exact. description thereof, attention being called to the three sheets of drawings Which accompany this application and form it part thereof.

, screw-threads. formed in thorough in castings used in connection with soteqvork of the screw-door type, in which type circular doors are held in closed position on the safebody by means of a screwwonnection; Pat-' ents No. 905,180 and No. 916,704, show safes of this type, each involving sofe-hodyhsving a. circular door-opening and s door-fitted to this opening, each being made of a casting of non-machineable metal, requiring grinding in the fitting-and finishing of the The threads used in the serew-con--- ork. nection whereby these doors are held in place are. produced in the rough in these castings and the machine here in -considers ticn is used to finish these threads and to shape them so that complementary threads fit'to each other. A related tyne of grindingmachine is shown in Patent No. 810,903 which however is not constructed in a .manner permitting also the grinding of screwthreuds because of limited capacity of adjustment Which prevents obtaining of certa'in positions of the grindingwheel necessary for the purpose. The machine which is shown in connection with this invention and which is used according to our method is constructed to provide possibility of obtaining theselvarious aolg'nstments and particularly such. necessary for the purpose of grinding screw-threads.

in the following speci dc clearance for the being beyond the finished and fitted, part of ticularly pointed out in the claims at the end.

thereof, will he found a full description of our i1l'2'tl1tl-' I1, together with its operation, Phi'lS and c nstruction. which latter is also illustrated in the accompanying three sheets of drawings. in which I Fir'ure 1., shows a front-view oi. 1 mo. Chill in Ponnwtien with which our invcntion is c fined. certain ports being shown in scct shows :1 top-view oi the whirling-wheel as it appears in this view. Fig. 3, shows a side-elemtion of the ma: chine with certain parts shown in section. Fig. 4, shows u top-view oi the grindingwlieel as it wars in this view. Fig. 5, is part of :1. top. 'eiv hf the object upon which the grinding wheel is operating. Fig. (3. is a vertical section on line S 6 of Fig. 1. T. is a hoi'iZ ntul'section on line 77 of Fig. v vs a detail. of construction res, A indicates a "cost-metal safe-hotly which I; is the door-opening and 7/ z: scrcw-iln'eznl provided in the jnmbsurface 9 oi this opening. circular door. not soon-n, is fitted to this jumh and 11 complementary tl "end is provided to hold the door in phi-cc. The thread shown in the drawing is mule thread and in the posi tion in which it appears 10 would be the on per side of it and 11 the lower one. This thread is roughly formed in the casting to be completed by :1. finishing tool and at its bottom it is enlarged as shown at 12 to pro tool, which clearance,

the thread, is not considered in the finishing work. 13 1s a. table npon 'ivhich this costing 1s held 111 a manner customary in machinetools, said tnhle being mounted for rotation in. a lower frome purt 14;. is rotated by means of a pinion l5 shop-"n 1n dotted lines which meshes into a toothed ring or crowngear provided on the underside of this table and not visible, in the drawings. 16' is a poWer-driven-shaft upon which this pinion is mounted. ln view of the nature of the metal a. grinding wheel O, supported for rotation is used for finishing the thread and for sizing it to a fit with reference to a co1nplementary thread on the door. The thread is produced by s compound feed-motion the grinding-Wheel and 31 letter s Yes to rotate .l upon it in :1 horizontal plane, while the grinding-wheel, without changing its position horizontally, moves at an angle to this plane. Thus by the motion of the table all parts of the rough thread are circumfereutially Sill'ljttfittl to the dCiiUl] 1 the grinding-wheel, while the same moves at the same time to follow the changing pitch-line of the thread. As nill be not d, this compound motion, rotary ot' the saliebody, and vertical 01? the grindingwheel, changes the position of the grind.ing-contact of this latter constantly and causes it to tolobject of our invention.

Since a line helically curved changes its formation and direction constantly as it progresses, no two points in it occupying the same plane, it follows that a grinding medium, in order to produce such a formation,

ninst move accordingly and so as to mainthin grinding contact with all points'oli this constantly changing llIlG. Tins requires primarily that'the grinding contact of the rinding medium be limited as much as possiblc' theoreticallyit should be limited to the geometrical point, because otherwise, it the "wheel grindsatmore than one point, that is ifs-considerable area of it is at once in grinding contact, flat places result which in stroy the true line of the helical curve. l or this reeson. the grinding-wheel is presented to the surface on which it is to grind in a tilted position and if grinding tor instance the upper side 1001 the thread, it would be in sposition as shown in Fig. i. so that as to the wheel, grinding-contact takes place only with a point/in the periphery or its upper edge, suidpoint being); indicated at e l 1 l, 2, 5, at and 5. 'lhis limited contactcan however he had only when this point etgrinding contact lies also at the same time in a plane which is radial to both the grinding'whecl and surface 9 which contains thescrew-thre d (observe Fig. 5) and pro- Videdfurther diet this plane is vertical to I the'pitch line of the screw as shown in Fig.

3,.(dotted lines) which shows the grindingw'he el. in. the same position as it is shown in 1. ti ports of the safe shown there and on which it is grinding being; removed. While'heretofore the grinding" contact has been spoken of as being-confined to a point in the periphery oi the wheel such a condicsn heinaintained in reality only for a limited time on account of the wear of the grinding-wheel which assrunes a tapering edge. 'llhereiiore this point soon assumes the of line which extends from it in:

wardly and increases in length as the width of the zone of wear increases, said line lying within the radial plane above mentioned. Observe Figs. 2, 4t and 5. The particular po-' sitionel relation between the point of grinding; contact on the grinding-wheel and the pitch line of the screw is maintained by reason of the rotation of the safe-body in one plane and the simultaneously proceeding movement of the grindingwheel in-a direction at an angle to this plane, both motions proceeding in properly proportioned ratio and by means and mechanism to be presently described.

The grinding-spindle 17 is supported in two bearings, one at each of its ends, which hearings, in order to assure perfect alinement, are by preference contained in a subslantially tubular frame-structure 18, which is supported on a carrier '19,

20 is a belt-pulley at the upper end of the grinding-spindle whereby this latter is 1'0- taled. The lower connection of frame L8 to this carrier is by a universal joint. D, which permits adjustment necessary to enaole tho grindi11gwl1eel to assume the various tilted positions described. The principal movement for this adjustment is bad at the upper end elf the iriunewhere it may be moved in or out with reference to carrier 19.

or laterally with respect thereto the lower part of the f'a-me simply following by turning); at the universal joint which acts as a pivot. This latter joint is substantially a ball and socket-joint, the ball being; formed by a spherical projection 91, fitted to a socket which is formed at one end of a screw 22, seated in the lower end of carrier 10. The ball is held in this socket by a bar 2?) extending-across it on the outer side and held to the carrier by screws 24:. fit its upper end frame .18 is connected to a frame E by bolts 25. said frame being,

conuemed to the carrier by two rearwardly extending wings :26 and by screws 27. Bolts 37 are T bolts and their heads oecupy'a T- slot 28 in frame it, said slot being curved on a radius which has its center in universal joint I). Screws 27 are seated in carrier 19 and extend into slots 29 in wings 2G, saidv slots being also formed on a radius. the center of which is likewise in'universnl joint I). it will now be seen thatithe tilted position vof the grindingqvheel shown in Fig.

1, required to cause it to grind on its edge,

may be obtained by swinging the spindleframe with the grinding-spindle to the right on frame E, after which bolts 25 are tightened in slot 28. If the wheel is grinding on the lower side ll of the screw-thread, the spindle would be swung to the opposite side as shown in dotted lines. To obtain the tilted position shown in Fig. 3, to cause the grinding-wheel to meet the inclination of thepitch-line of the screw, frame E with upper end of the spindle-frame, screws Ql at its lower 'end are sufiiciently eased to permit-a free movement of the members of the balland socket-joint. These screws although closely fitted against opposite sides of ball 21,"do not interfere with this limited movemeat of the same, because rouiul-bottouied notches 31. are provided in said ball. Fig, 8.) The adjustment had at the upper end of the spindle-frame may be aided and corrected if necessary, by moving screw 22 whereby the lower end of the spindle may be moved in or out with reference to carrier it After all adjustments are completed screws 24 are also tightened, so that the spindlesupporting-frame l8 and carrier l9 become now a rigidly connected structure which is supported to be movable to and from table 13 which carries the object A.- For such purpose carrier 19 is slidably fitted to a cross-head 32 and provided with a rack 33 which is engagedby' a pinion 34, whereby said carrier is caused to move either up or down to follow the'inclination of the pitch of'screw-thread i). The actuation of this pinion is obtained from a shaft 35 which carries a worm-wheel 36, rotated by a worm 37. This latter is connected to a shaft 38, mounted on a rail 39 which is supported on upright frame-members 40. This support may be one vertically adjustable by means of screws 4H in a manner customary in machinetools. Shaft- 38 is rotated by means of gears 42, 4-3 and 44, the latter rotated by a set of bevel-wheels 45 from an upright shaft This latter carries a bevel-wheel 47 and may be rotated in either direction by either one of two bevel-wheels 48, L8, shiftably mounted upon a'power-drivenshaft ll). By

changing the direction of rotation of shaft 46, worm 37 is caused to rotate accordingly and carrier 19 may be directed to move either up or down. Cross-head is slidably mounted on rail 39 and provided with a nut 51, engaged by a screw 52 mounted in rail 39, so that-,when said screw is rotated. which may be by means of a crank, the head is is caused to move transversely on rail 39. Worm 37 follows the head so as to maintain engagement with worm-wheel 36, its engagement with shaft 38 being by a customary spline. I

he parts for positioning are handled as follows: The grinding-wheel, having been raised by means of carrier 19, to permit placing of object A, and moved laterally by head 32 on rail 39 to be in proper position above the object, is lowered again by movement of the carrier until it is opposite one end of thread 7). Next the two tilted positions of the grinding-wheel, shown respectively in F; 1 and 2-3, are obtained by adjusting the grinding-spindle on said carrier in the manner described. This adiustiuent having been determined, the grindingwheel is moved into thread Z) as shown in Fig. l, by moving crosshead 32, which is done by rotating screw 52. cut circumferentially all around through the thread is taken. after which rotation of table. 13 and angular movement of the grinding-wheel is stopped, and the latter moved out of the thread by shifting cross-head 32. Since one cut is rarely suflicient to cover the surface to be ground, additional cuts are taken, the wheel for each-subsequent cut and while maintainingits tilted position bcinp deeper into the thread, this being done after the wheel hascach time'bcen brought. opposite one of the ends of the thread. We prefer to grind while the grinding-wheel follows the pitchline with a downward movement and there-' fore, for each re-setting, the wheel is raised to be opposite the high end ofthe thread,

after which it is set into the same and the compound feed-motion by table and carrier is caused to resume. A gage 53, adjustably mounted on the rail, aids the determination of the extent of these successive ire-settings.

The uprigl'it movement of carrier ll) do scribed before as proceeding from wormwheel 36 and worm 37 and whereby the grinding-wheel iscaused to follow the pitch of the, screw, is rather slow and therefore means have been provided whereby, for setting the grinding-wheel and for moving it vertically with respect to the work, carrier 19 may be moved more quickly by hand and at which time worm-wheel 36 and worm 37 are not used for the purpose. These means consist of a hand-wheel 54., loosely mounted and of an arm rigidly CODHCClQl'l to shaft 35 which carries worm-wheel 3b. This arm carries a iocltingpin 56 which may be nianip'ulated by means of a handle 5? to enter into any one of a number of holes 58 provided in the hub of the handwheel and whereby, when said pin occupies one of these holes, said. huud-wheel is positively locked to shaft 35. On its rear side, the hand-wheel carries a worm v59, endwise con fined, but free for rotation, said worm engaging a worm-wheel G1, rigidly mounted upon a hollow shaft 62 which carries pinion 34 and is sleeved upon shaft 35 and supported in a. bearing 63 forming part .of cross-head 32. It will now be seen that if hand-wheel 54 by means of pin 56 is locked to shaft 35 so as to be driven by it, and power-driven worm-shaft 38 is caused to rotate, machine-operated change of position of the rindiiw-wheel whereb it is caused.

to follow pitch-line, is bad by means of -arrier 19 which moved by pinion 34 on hollow shaft 62, said shaft being driven by hand-wheel 54 to which it is held by wormwhcel (31 and worm 59. If the quicker, hand-operated movement. of carrier 19 is desired for the purpose. of setting the grin ling-wheel and for adjusting its position above table 13, hand-wheel b4: discon-- nccted from power-driven shaft. 35 by manipulation of locking-pin by n'zeans of its handle 57, after which the grinding-wheel may be quickly raised or lowered. Vy hci'i the hand-wheel is used in this manner for setting the grinding-wheel, power-operation of shaft 35 is preferably stopped by use of a conveniently located clutch and shaft 02 is manipulated .directlyby the hand-wheel until the grinding-wheel approaches the desired position after which locking-pin 5G is t rned into the nearest one of holes Z355. 'lhis manipulation is sufficient for merely raising or lowering the grindingavheel with respect to the work. Closer adjustment necessary to set the wheel exactly to the cut is had by i I'tlYUP" rotation of shaft (32 ohtaincd biy manipulation of worm 52), by means 0' asuitahle wrench, whereby, by

means of worm-wheel 6i on said shaft 62,

additional movement of carrier 19 is had until the grinding-w11eel is in the exact positicn desired for grinding.

When as in the case shown, the screwthread to be ground does not run out in the open, that is extend to the'edges of surface 9 in which it is contained, rotation of table 13 as well as the movement of carrier 19 must stop each time as soon as the end of the thread and the grinding-wheel come together. This is prefe'ably done automati cally and by means of a stop (34 adjusted to proper position on table 13 and which by means of a trip-lever mechanism 5 acts upon a clutch adapted to control operation of a general drivingshaft from which the operation of shafts 16 and il) proceeds.

The use of customary means for changing speeds and for reversing motions, an alogous to similar constructions in machine-tool;- is presumed, but since such means may be a o plied in various ways they are not shown in detail.

The complementary thread on the door which is fitted to the opening in the safebody A, is ground in a similar way. However since the door is not so heavy, a lighter machine-tool of the lathe-type may be used, by the chuck of which the door is held. The grinding-wheel is supported in an analogous manner, that is in one which permits the grinding spindletobe adjusted in the directions here described, so as to obtain the limited grinding-contact and to fit the pitch of the screw-thread. The method would however be substantially the same when used under the arrangement and with the means alluded to and would produce toe earners Wniic as shown the thread to be finished is located in an annular surface, tapering inwardly, that is conican disposed, the

mll jit', procedure is followed if the thread were to be ground in a cylindrical surface. in other words, the thread is .ground as if it were contained in a, cylindrical surface and taper is; not considered. A true screw-line results nevertheless, with this difference however, that the thread becomes dee or as it approaches the inner ed e of sur'ace 9,

which however is not ObJectiOnable, provided the thread is started deep enough at the largest diameter of the taper.

irlavingdescribed our invention, we claim as new:

i. 'i he method. of grinding screw-pitched surfaces which consists of carrying such a surface around a rotating winding-wheel,

b of moving this latter in a ratio corresponding to the pitch of tl 2 surface and in a direction at an angle to the plane in which the surhice moves and of maintaining grinding contact while these movements of grindingwheel and of surface proceed.

The method of grinding a screw-thread which consists of moving t e'surface which contains the thread pasta rotary grinding'wheel which is tilted with its flat side at an angle to the surface on which the wheel grinds and with the axis of its rotation located in a plane disposed at right angles to the pitch of the screw-thread.

3. The method ofugrinding screw-threads which consists of carrying the surface which to contain the thread around a rotating grindingwheel, of moving this latter in a atio corresponding to the p tch of the thread past this surface and in a direction at right angles to the plane in which the surface moves and of maintaining grinding contact while these movements of grinding wheel and of surface proceed, said grinding contact being limited and lying at the end of a radius of the grinding-wheel which when edcuded intersects with the axis about c surface which receives the thread 1 which also lies in a plane disght angles to the pitch-line of the thread.

The methodofproducing by grinding a screw-threadin anannular, tapering "sur-K face, which consists ofcarrylng thls surface:

5 The method of producing a screwthread by the compound feed motions of an objectsupporting carrier which has a, rotary motion and of a rotating grinding-wheel which moves in a linear directiomthe mo- 101:1 prsiuces screw-threw in an annum which consists 0i supporting a T Wheel so tn prmcice a Hmitad m a point in $111 n s line an t' whee exiem m 11 said point 01" moving 110 :2,

.a about Hm giinc'img a Wing the gfinding at an angle to the m; m. w 

